Many electronic devices are tested for electrical and/or optical properties during manufacturing by automated test systems. Typical automated test systems use precision electrical and/or optical test equipment to find values associated with electrical and optical properties of a device and either accept, reject or sort it into an output category depending upon the measured values. For miniature devices, automated test systems are often designed to handle bulk loads, where the manufacturing process creates a volume of devices which have substantially identical mechanical characteristics such as size and shape but differ in electrical and/or optical characteristics. It is common practice to build a volume of devices with electrical and optical properties which generally fall within a range and rely on testing to sort the devices into commercially useful groups with similar characteristics. Typical electronic devices tested and sorted in this fashion include passive components such as resistors, capacitors and inductors and active electronic devices such as digital or analog integrated circuits or light emitting diodes.
These devices are often supplied to the automated test system as containers filled with devices. Typically the automated test system must extract a single device from the bulk load of devices in a process called singulation, orient the device and fixture it so the test equipment can perform the desired tests. Testing often requires probing the device, wherein electrical leads are brought into contact with the device to permit signals and power to be applied to the device and to monitor responses to the inputs. The task of the automated test system is to determine the electrical characteristics of devices and sort the devices into groups depending upon those characteristics. The automated test system typically singulates devices onto a track where the devices are indexed past one or more test stations where various electrical and/or optical properties of the device are tested and the results stored. As the devices are subsequently indexed past the sorting stations, the devices are removed from the track and deposited in one of a number of bins depending upon the results of the preceding tests. A typical prior art automated test system is shown in FIG. 1, where a track 2 with locations 3, 4 spaced “p”=pitch distance apart are indexed by the track 2 in the direction of the arrow along a route to the loader 5 where bulk parts 6 are loaded 7 onto the track. The device 7 is indexed by the track 2 along the route to location 10 where it is tested by test station 9 and the results stored on a controller (not shown). The device 7 is subsequently indexed by track 2 along the route to location 11 where the sort tube 12 removes the device 13 from the track 2 for sorting.
U.S. Pat. No. 5,842,579 ELECTRICAL CIRCUIT COMPONENT HANDLER, inventors Douglas J. Garcia, Steven D. Swendrowski, Mitsuaki Tani, Hsang Wang, Martin J. Twite, III, Malcolm Hawkes, Evart David Shealey, Martin S. Voshell, Jeffrey L. Fish and Vernon P. Cooke, Dec. 1, 1998, assigned to the assignee of this invention, discloses a rotary disk test machine with multiple tracks able to test multiple parts at once. Another exemplary system that uses duplicate tracks to test devices in parallel is the MT20 LED tester manufactured by Mirae Corporation, Chungcheongnam-Do 331-220, Korea. The track holding the devices does not have to be rotary. U.S. Pat. No. 4,747,479 DEVICE FOR THE TESTING AND/OR PROCESSING OF SMALL COMPONENT PARTS, inventor Jakob Herrman, May 31, 1988 discloses a linear belt to hold parts under test. What these disclosures do not consider is the possibility of testing more than one device in parallel without having to duplicate the tracks that feed parts to the test stations whether they are rotary or linear.
What is needed, then, is an automated test system for testing and sorting miniature electronic devices that can test at least two devices in parallel and sort them at high speed using a single track to deliver devices to the test stations.